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Chapter 7

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  1. Chapter 7 Anatomy and Physiology 7:11 Digestive System DHO 7th edition

  2. 7:11 Digestive System • Also known as the gastrointestinal system • Responsible for • Physical and chemical breakdown of food for use by the body • System consists of the alimentary canal and the accessory organs

  3. Alimentary Canal • Long muscular tube that begins at the mouth and ends at the anus, includes: • Mouth (oral cavity) • Pharynx • Esophagus • Stomach • Small intestine • Large intestine • Anus • Accessory organs: salivary glands, tongue, teeth, liver, gallbladder, pancreas

  4. Mouth, Buccal, or Oral Cavity • Receives food as it enters the body • Actions in the mouth • Food is tasted, broken down by the teeth, lubricated and partially digested by saliva, and swallowed • Teeth • Break down food by chewing and grinding • Process called mastication • Tongue • Muscular organ • Contains specialized receptors called taste buds • Allow us to taste sweet, sour, salty and bitter sensations

  5. Mouth, Buccal, or Oral Cavity (cont.) • Hard palate • Bony structure that forms roof of mouth • Separates mouth from nasal cavities • Soft palate • Posterior to hard palate • Separates mouth from nasopharynx • Uvula is a cone-shaped muscular structure • Located in middle of soft palate • Prevent food from entering nasopharynx during swallowing

  6. Mouth, Buccal, or Oral Cavity (cont.) • Salivary glands • Three pairs • Parotid • Sublingual • Submandibular • Produce saliva

  7. Mouth, Buccal, or Oral Cavity (cont.) • Saliva • Lubricates mouth during speech and chewing • Moistens food – easier to swallow • Contains an enzyme called salivary amylase • Begins chemical breakdown of carbohydrates, or starches, into sugars that can be taken into the body • Bolus • Term used to describe chewed food mixed with saliva • When swallowed, enters pharynx

  8. Pharynx • Carrier for both air and food • Carries food bolus to the esophagus • When bolus swallowed, muscle action causes epiglottis to close to prevent food from entering respiratory tract

  9. Esophagus • Muscular tube dorsal to the trachea • Carries bolus to stomach • Peristalsis, a rhythmic wavelike involuntary movement of the muscles, moves food toward stomach • Peristalsis occurs in rest of digestive tract, moving food in a forward direction • http://www.youtube.com/watch?v=YJ34Qx6hzJk

  10. Stomach • An enlarged portion of the alimentary canal • Receives food from esophagus • Mucous membrane lining contains rugae (folds) to increase surface area • Rugae disappear as stomach expands • Cardiac sphincter • Circular muscle between esophagus and stomach • Closes after food enters stomach to prevent it from going back into esophagus • Pyloric sphincter • Circular muscle between stomach and small intestine • Prevents food from entering small intestine until it is ready • Food usually remains in stomach about 2–4 hours

  11. Stomach • Gastric juices • Produced by glands in stomach • Converts food into semifluid material, called chyme • Contain hydrochloric acid and enzymes • Hydrochloric acid • Kills bacteria • Facilitates iron absorption • Activates the enzyme pepsin • Enzymes in gastric juices • Lipase – starts chemical breakdown of fats • Pepsin – starts protein digestion • Rennin – only present in infants, not adults, to help digest milk

  12. Small Intestine • About 20 feet long; 1 inch in diameter • Receives food from the stomach in the form of chyme • Small intestine divided into 3 sections • Duodenum • First 9-10 inches • Bile, from the gallbladder and liver, and pancreatic juice, from the pancreas, enter this section • Jejunum • Middle section of small intestine • About 8 feet in length • Ileum • Final 12 feet of the small intestine • Connects with the large intestine at the cecum (continues)

  13. Small Intestine(continued) • Process of digestion is completed in the small intestine • Products of digestion are absorbed into the blood stream for use by the body cells • Intestinal juices (produced by the small intestine) • Contain enzymes maltase, sucrase and lactase which break down sugars into simpler forms • Contain enzymes known as peptidases with complete the digestion of proteins • Contains enzymes steapsin (lipase) which aid in the digestion of fats

  14. Small Intestine(continued) • Bile • Emulsifies (physically breaks down) fats • Pancreatic juice • Contain enzymes that complete process of digestion • Amylase of amylopsin (act on sugars) • Trypsin and chymotrypsin ( act on proteins) • Lipase or steapsin (acts on fats)

  15. Small Intestine(continued) • Villi • Fingerlike projections on walls of intestine • Contain blood capillaries and lacteals • Capillaries absorb digested nutrients and carry them to the liver - they are either stored or released into the general circulation for use by the body cells • Lacteals absorb most of the digested fats and carry them to the thoracic duct in the lymphatic system, which releases them into the circulatory system • When food has finished its journey through the small intestine, only wastes, indigestible materials, and excess water remain

  16. Large Intestine Final section of the alimentary canal • About 5 feet long; 2 inches in diameter • Functions • Absorption of water and any remaining nutrients • Storage of indigestible materials before they are eliminated from the body • Synthesis (formation) and absorption of some B-complex vitamins and vitamin K by bacteria present in the intestine • Transportation of waste products out of the alimentary canal

  17. Large Intestine (continued) Divided into a series of connected sections • Cecum • First section that is connected to the ileum of the small intestine • Contains a circular muscle, the ileocecal valve, which prevents food from returning to the ileum • Also contains a small projection called the vermiform appendix

  18. Large Intestine (continued) • Colon • Next section of large intestine • Has several divisions • Ascending colon continues up the right side of the body • Transverse colon extends across the abdomen, below the liver and stomach above the small intestine • Descending colon extends down the left side of the body • Contacts to the sigmoid colon, an s-shaped section that joins the rectum

  19. Large Intestine (continued) • Rectum • Final 6-8 inches • Storage area for indigestible and wastes • Has a narrow canal, the anal canal, which opens to the anus (hole) • Fecal material, or stool, is the final waste product of the digestive process • Expelled through this opening

  20. Accessory Organs • Liver • Gallbladder • Pancreas

  21. Liver • Largest gland in the body • Accessory organ for digestive system • Location • Under the diaphragm in upper right quadrant of the abdomen Functions • Secretes bile, used to emulsify fats • Bile also makes fat water soluble which is necessary for absorption • Stores sugar in the form of glycogen • Glycogen is converted to glucose and released into bloodstream when needed

  22. Liver (continued) • Stores iron and certain vitamins • Produces heparin which prevents clotting of blood • Produces blood proteins, such as fibrinogen and prothrombin which aid in clotting • Produces cholesterol • Detoxifies (makes less harmful) substances • Destroys bacteria taken into blood from the intestine

  23. Healthy liver

  24. Gallbladder • Small muscular sac • Location – under the liver, attached to it by connective tissue • Function • Stores and concentrates bile it receives from the liver • Bile needed to emulsify fats • When bile is needed, gallbladder contracts and pushes bile through cystic duct into the common bile duct • Common bile duct drains into the duodenum

  25. Pancreas • Fish-shaped glandular organ located behind the stomach • Produces pancreatic juices to digest food • Enters duodenum through pancreatic duct • Produces insulin which is secreted into the blood stream • Insulin regulates metabolism (burning) of carbohydrates to convert glucose (blood sugar) to energy

  26. Diseases and Abnormal Conditions • Appendicitis • Cholecystitis • Cirrhosis • Constipation • Diarrhea • Diverticulitis • Gastroenteritis • Hemorrhoids • Hepatitis • Hernia • Pancreatitis • Peritonitis • Ulcer • Ulcerative Colitis

  27. Appendicitis • Acute inflammation of the appendix • Usually result from obstruction or infection • Symptoms • Generalized abdominal pain, later localizes to lower right quadrant • Nausea and vomiting • Mild fever • Elevated wbc count • Treated by appendectomy (surgical removal of appendix • If appendix ruptures, infectious material spills into peritoneal cavity – peritonitis (very serious condition)

  28. Cholecystitis • Inflammation of the gallbladder • If gallstones (crystallized cholesterol, bile salts, and bile pigments) – known as cholelithiasis • Symptoms • Indigestion – usually occurs after eating fatty foods • Nausea and vomiting • Pain under the rib cage that radiates to right shoulder • If bile duct gets blocked, gallbladder can rupture and cause peritonitis • Treatment • Low-fat diet, lithotripsy (shock waves to shatter stones), cholecystectomy (surgical removal)

  29. Cirrhosis • Chronic destruction of liver cells accompanied by the formation of fibrous connective and scar tissue • Causes • Hepatitis • Bile duct disease • Chemical toxins • Malnutrition associated with alcoholism

  30. Cirrhosis (cont.) • Symptoms vary – become more severe as it progresses • Liver enlargement • Hematemesis (vomiting blood) • Anemia • Nosebleeds • Indigestion • Jaundice (yellow discoloration) • Nausea • Ascites (fluid accumulation in peritoneal cavity) • Edema in the lower extremities • When liver fails • Disorientation • Hallucinations • Hepatic coma • Death

  31. Cirrhosis (cont.) • Treatment • Directed toward preventing further damage • Alcohol avoidance • Proper nutrition • Vitamin supplements • Diuretics • Rest • Infection prevention • Appropriate exercise • Liver transplant

  32. Constipation • Fecal material remains in colon too long • Excessive reabsorption of water occurs • Causes • Poor bowel habits • Chronic laxative use – lead to “lazy” bowel • Low fiber diet • Certain digestive diseases • Treatment • High fiber diet • Adequate fluids • Exercise

  33. Diarrhea • Frequent watery stools • Causes • Infection • Stress • Diet • Irritated colon • Toxic substances • Extremely dangerous in infants and small children because of excessive fluid loss • Treatment • Eliminate cause • Provide adequate fluid intake • Modify the diet

  34. Diverticulitis • Inflammation of the diverticula, pouches (or sacs) that form in the intestine as the mucosal lining pushes through the surrounding muscle • Fecal material and bacteria become trapped, inflammation occurs • Can result in rupture of sac, leading to peritonitis

  35. Diverticulitis (cont.) • Symptoms • Vary according to amount of inflammation • Abdominal pain • Irregular bowel movements • Flatus (gas) • Constipation or diarrhea • Abdominal distention • Low-grade fever • Nausea and vomiting • Treatment • Antibiotics • Stool softening medications • Pain meds • High fiber diet • Possible surgery to remove affected section of colon

  36. Gastroenteritis • Inflammation of the mucous membrane that lines the stomach and intestinal tract • Causes • Food poisoning • Infection • Toxins • Symptoms • Abdominal cramping • Nausea & vomiting • Fever • Diarrhea • Treatment • Rest • Increased fluid intake • If severe • Antibiotics • IV fluids • Medications to slow peristalsis

  37. Hemorrhoids • Painful dilated or varicose veins of the rectum or anus • Causes • Straining to defecate • Constipation • Pressure during pregnancy or labor • Insufficient fluid intake • Laxative abuse • Prolonged sitting or standing • Symptoms • Pain • Itching • Bleeding • Treatment • High-fiber diet • Increased fluid intake • Stool softeners • Sitz baths or warm moist compresses • Hemorrhoidectomy

  38. Hepatitis • Viral inflammation of the liver • Types of hepatitis viruses • Hepatitis A • Highly contagious • Transmitted via contaminated food or water • Vaccine available • Hepatitis B • Serum hepatitis • Transmitted via body fluids (blood, serum, saliva, urine, semen, vaginal secretions, breast milk) • More serious than Hepatitis A • Can lead to chronic hepatitis or cirrhosis of the liver • Vaccine available (recommended for all health care workers)

  39. Hepatitis (cont.) • Hepatitis C • Transmitted and spread through body fluids • Main methods of transmission • Sharing needles while injecting drugs • Accidental needle stick with contaminated sharps at work • Passed from infected mother to infant during birth • Much more likely to progress to chronic hepatitis and/or cirrhosis • Hepatitis D and Hepatitis E are other strains indentified

  40. Hepatitis (cont.) • Symptoms • Fever • Anorexia • Nausea and vomiting • Fatigue • Dark-colored urine • Clay-colored stool • Myalgia • Enlarged liver • Jaundice • Treatment • Rest • High protein and calorie diet, low in fat • Liver transplant if liver is severely damaged

  41. Hernia • Rupture whereby an internal organ pushes through a weakened area or natural opening in a body wall • Hiatal hernia • Stomach protrudes through the diaphragm and into the chest cavity through the opening for the esophagus • Inguinal hernia • Section of small intestine protrudes through the inguinal rings of the lower abdominal wall

  42. Hernia (cont.) • Symptoms • Heartburn • Stomach distention • Chest pain • Dysphagia • Treatment • Bland diet • Small frequent meals • Staying upright after eating • Surgical repair (Herniorrhaphy)

  43. Pancreatitis • Inflammation of the pancreas • Pancreatic enzymes begin to digest the pancreas itself • Pancreas becomes necrotic, inflamed and edematous • If damage extends to blood vessels in pancreas, hemorrhage and shock occur

  44. Pancreatitis (cont.) • Causes • Excessive alcohol consumption • Blockage of pancreatic ducts by gallstones • Idiopathic (unknown) • Symptoms • Severe abdominal pain – radiates to back • Nausea & vomiting • Diaphoresis • Jaundice – if common bile duct blocked • Treatment • Depends on the cause • Cholecystectomy if gallstones are cause • Analgesics and nutritional support if alcoholism or idiopathic cause • Poor prognosis and death for this cause

  45. Peritonitis • Inflammation of the abdominal peritoneal cavity • Usually occurs when rupture in intestine causes intestinal contents to enter peritoneal cavity • Ruptured appendix or ruptured gallbladder can also cause this condition • Symptoms • Abdominal pain and distention • Fever • Nausea and vomiting • Treatment • Antibiotics • If necessary, surgical repair of damaged intestine